sustainability Review Management of Crop Residues for Improving Input Use Efficiency and Agricultural Sustainability Sukamal Sarkar 1,2 , Milan Skalicky 3 , Akbar Hossain 4,* , Marian Brestic 3,5 , Saikat Saha 6 , Sourav Garai 1 , Krishnendu Ray 7 and Koushik Brahmachari 1 1 Department of Agronomy, Faculty of Agriculture, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia 741252, West Bengal, India; [email protected] (S.S.); [email protected] (S.G.); [email protected] (K.B.) 2 Office of the Assistant Director of Agriculture, Bhagwangola-II Block, Directorate of Agriculture, Government of West Bengal, Murshidabad 742135, West Bengal, India 3 Department of Botany and Plant Physiology, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamycka 129, 165 00 Prague, Czech Republic; [email protected] (M.S.); [email protected] (M.B.) 4 Bangladesh Wheat and Maize Research Institute, Dinajpur 5200, Bangladesh 5 Department of Plant Physiology, Slovak University of Agriculture, Nitra, Tr. A. Hlinku 2, 949 01 Nitra, Slovakia 6 Nadia Krishi Vigyan Kendra, Bidhan Chandra Krishi Viswavidyalaya, Gayeshpur, Nadia 741252, West Bengal, India; [email protected] 7 Sasya Shyamala Krishi Vigyan Kendra, Ramakrishna Mission Vivekananda Educational and Research Institute, Arapanch, Sonarpur 741252, West Bengal, India; [email protected] * Correspondence: [email protected] Received: 5 November 2020; Accepted: 21 November 2020; Published: 24 November 2020 Abstract: Crop residues, the byproduct of crop production, are valuable natural resources that can be managed to maximize different input use efficiencies. Crop residue management is a well-known and widely accepted practice, and is a key component of conservation agriculture. The rapid shift from conventional agriculture to input-intensive modern agricultural practices often leads to an increase in the production of crop residues. Growing more food for an ever-increasing population brings the chance of fast residue generation. Ecosystem services from crop residues improve soil health status and supplement necessary elements in plants. However, this is just one side of the shield. Indecorous crop residue management, including in-situ residue burning, often causes serious environmental hazards. This happens to be one of the most serious environmental hazard issues witnessed by the agricultural sector. Moreover, improper management of these residues often restrains them from imparting their beneficial effects. In this paper, we have reviewed all recent findings to understand and summarize the different aspects of crop residue management, like the impact of the residues on crop and soil health, natural resource recycling, and strategies related to residue retention in farming systems, which are linked to the environment and ecology. This comprehensive review paper may be helpful for different stakeholders to formulate suitable residue management techniques that will fit well under existing farming system practices without compromising the systems’ productivity and environmental sustainability. Keywords: residue management; soil degradation; GHGs; resource use efficiency 1. Introduction Agriculture and associated sectors, which are the mainstay of economies in many developing and undeveloped countries, covering almost 82% of the world’s population directly or indirectly, need to Sustainability 2020, 12, 9808; doi:10.3390/su12239808 www.mdpi.com/journal/sustainability Sustainability 2020, 12, 9808 2 of 24 be sustainable for bringing about greater prosperity of human beings. This requires the introduction, adoption, and development of improved production technologies [1]. The technologies conserving resources in agriculture are the most valuable keys to ensure sustainability in food production. The adoption of such input-intensive agricultural practices often leads to serious depletion of soil nutrients. The use of modern heavy farm implements like the combine harvester, rotavator, and seed cum fertilizer drill is increasing day by day. The use of the seed cum fertilizer drill and combine harvester in the rice–wheat system of the Indian subcontinent has increased manyfold in the last few years [2,3]. The production of crop residue in modern input-intensive agricultural practices was also linearly increased. Farmers often burn these crop residues in-situ, which leads to serious environmental impacts [4–6]. Burning of crop residues has a serious negative impact on human health as well as environmental consequences. It was reported that in-situ crop residue burning in Asian countries accounted for more than one-third of total biomass burning [5]. The particulates (PM) released from such burning, like PM10, PM2.5, and greenhouse gases (GHGs), are also responsible for environmental pollution [5,7]. Crop residue management is a well-known and widely accepted practice for controlling various soil physical, chemical, and biological functions. Crop residues incorporate a large number of nutrients in the soil for crop production and affect soil water movement, runoff, and infiltration. In a conservation agriculture (CA) system, successful management of crop residues is an integral part, and the maximum benefit of CA can only be achieved with in-situ management [8]. However, decomposition of crop residues has both positive and negative impacts on crop production. The role of the researcher is central in employing the positive effects of crop residue management practices and improving positive impact on the environment [9]. Soil management with crop residues covers a wide range of aspects, like residue decomposition, soil erosion control, nutrient recycling and availability to plants, control of weed pests, and various conservation practices related to tillage for maximizing crop yields [10]. The annual cycling of plant nutrients is important in the plant–soil ecosystem in order to maintain a productive agricultural system and to facilitate better nutrient mobilization within the system [11]. It is reported that soil, air, and water, which have tremendous interaction with plants, release various essential inorganic nutrient elements for plant growth [7]. Apart from this, carbon-enriched crop residues serve as the main food source for soil microorganisms and initiate the biological nutrient cycling framework. Throughout microbial decomposition of crop residues, different chemicals are released in soil and can be properly utilized by plants and other living organisms [2]. Plant availability of NPK nutrients from crop residues mostly depends on different soil physical, chemical, and biological processes. Integrated management with fertilization and the amount of crop residue remaining for incorporation in the crop field determine the degree of cycling and plant availability of nutrients from crop residues. Management of crop residues for a better C sequestration and the amount and site of crop residue application coupled with optimum use of N fertilizer are necessary for promoting soil organic matter [12,13]. In the present review, we have focused on the different aspects of crop residue management, like the impacts of residues, utilization of natural resources, and strategies to be formulated for better residue management in farming systems, which are largely related to the present-day environmental issues. Efficient crop residue management strategies for sustainable crop residue management without compromising the crop yield must be framed for maximizing the input use efficiency for food and environmental security. 2. Intensive Agriculture and Crop Residues: Present Status The modern intensive agricultural system depends on the heavy application of external inputs. Farmers who practice such modern input-intensive agricultural practices usually follow intensive crop rotation practices, and the lands remain fallow during a crop season in a cropping year [14]. The adoption of intensive agricultural practices coupled with high-yielding varieties and modern irrigation facilities often leads to micronutrient deficiencies and decreased soil fertility. It has been reported that a steady Sustainability 2020, 12, 9808 3 of 24 Sustainability 2020, 12, x FOR PEER REVIEW 3 of 24 shift from the use of different organic manures and traditional plant nutrient elements (farmyard promisingmanure, composts, technique etc.) to resolve instead ofthis chemical problem fertilizers [15]. In addition, is considered these as modern a most promising intensive techniqueagricultural to practicesresolve this often problem cause [15 severe]. 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